I once spent days interviewing an extremely talkative American architect. He filled eighteen sides of audiotape and then told me that he needed to get down to the business of sharing his philosophies with me. Yikes!
He often referred to the shibui in his work and said it was a deep, old Japanese concept. He supplied only vague definitions, and when I tried to research shibui on my own, I didn’t get very far.
At any rate, I now find that the kanji for shibui is 渋い. Shibumi, 渋み, means the same thing … but what does it mean?! Dictionary definitions aren’t of much help. The closest interpretation I can find is “elegant” or “restrained elegance.” Wikipedia does shed light on the issue by referring to shibui/shibumi as “events, performances, people or objects that are beautiful in a direct and simple way, without being flashy.”
Oh, is that all?! Funny that a word about simplicity confounded me for all these years!
Postscript: A few days after writing this text, I came across 渋谷駅. Again, I encountered it in the context of architecture, as I’ve been asked to write about the new subway station in Shibuya (in Tokyo). I Googled the station name in English and ended up confronting quite a bit of Japanese. No matter how much I love kanji, I always view long Japanese passages with trepidation, certain that I won’t understand (especially if native speakers wrote the text for other native speakers). And then guess what jumped out at me, thanks to my new awareness of 渋 as shibu(i)? I immediately recognized 渋谷駅 as “Shibuya station.”
The last character is 駅 (eki: station). And I should have known that the middle one, 谷, means “valley.” Oh my goodness, just look how 渋谷 could break down: to have diarrhea + valley! Shibuya is the valley where one has diarrhea! Or it’s the valley of restrained elegance. Or maybe it’s the valley where one can only be elegant in a restrained way, owing to the onset of diarrhea… No, no, it’s probably just a “quiet valley,” since 渋 can mean “subdued, quiet.” I need to hold onto that image as I write the article about Shibuya station!
Post-postscript: I shared some of these thoughts with a native speaker, who felt astounded that I was associating 渋 in any way with diarrhea, as neither his life experience nor his reference books supported that, except for one word in his dictionaries, 渋り腹 (shiburibara), which means “diarrhea-like bowel pains” or “a strong urge to go, coupled with an inability to do so.”
So I returned to my reference materials and found that three sources (Breen, Spahn, and Nelson) do define shiburu as “to hesitate, to be reluctant, to have loose, painful bowel movements.” (I took the wording there from Nelson.) This overlap puzzled me, because diarrhea is the opposite of a delay.
Then Henshall came to the rescue. He has pointed out that 渋 contains both the water radical 
and 止, meaning “to stop.” Originally, he says, 渋 meant “not flow smoothly,” which came to be associated with “tardy” and “delay/hesitate.” Some scholars feel that the associated meaning of “astringent” stems from the idea of preventing juices from flowing. Hmm … If anything, diarrhea seems to be a case where the juices are flowing too well! But if we return to the definition of “a strong urge to go, coupled with an inability to do so,” I think we’ve solved the mystery, as that definition hints at being caught between strong contractions and a painful delay in production!
Oh, and on the subject of delays, I now realize that we briefly looked at 渋 in an earlier blog. Somehow, I hadn’t connected traffic jams to sour fruit, Shibuya, shibui, or diarrhea!
